A rolling mat used in hand rolling operations of norimaki (vinegared rice rolled in dried seaweed), makizushi (sushi roll), datemaki (sweetened rolled omelet mixed with fish paste), and the like is formed in a bamboo screen shape. The rolling mat is generally constituted by a plurality of elongated rib parts juxtaposed in a direction in which a food material is rolled and a string material part for connecting the plurality of rib parts.
Conventionally, a bamboo material which has relatively high rigidity and a smooth surface is suitably used as the rib parts, and a twisted yarn of a cotton thread such as kite string which exhibits high flexibility and which enables necessary elongation is used as the string material part.
Since such a rolling mat comes into contact with food materials such as seaweed, rice grains, raw fish, tamagoyaki (Japanese style omelet), and the like, easiness of sanitation management is required. However, the bamboo material and cotton threads that form the rib parts and the string parts have the following problems. Bamboo material and cotton threads absorb moisture and are difficult to clean. In addition, with bamboo material and cotton threads, it is difficult to remove detergent and stains having penetrated therein, mold and bacteria growing inside, and the like. While mold, bacteria, and the like can be sterilized with hot water, hot water sterilization is likely to impair durability of the rolling mat. Furthermore, bamboo material has risks including being more susceptible to fine splits due to bamboo fibers and detached hangnails getting mixed into the food material. Moreover, while the rolling mat must be dried since a wet rolling mat dampens seaweed, since bamboo material and cotton threads require a long time to dry, cleaning can only be performed around once a day which is not satisfactory in terms of sanitation.
In consideration thereof, a rolling mat formed of plastic has recently been developed as described in Patent Document 1 as a countermeasure to such problems. The rolling tool (rolling mat) described in Patent Document 1 includes a plurality of rib materials having linear chevron cross sections and thinned parts between the plurality of rib materials, and the rib materials and the thinned parts are integrally formed of silicone rubber. In addition, since the silicone rubber is flexible, the rolling mat is advantageous in that it is easy to roll and is sanitarily favorable.